The clones that survived have yellow tips

I recently transplanted 2 clones in rockwool to soil. They had been in the terrarium for two weeks and were not showing signs of roots,and the other six of the sisters had died,so I took the 2 that were alive and potted them.They have been in the soil for a week now,and they are healthy green,but the leaf tips are yellow around the edges and tips of the leaves. I fertilized them with a quarter of the normal dosage today of alaska fish fert.(all i could afford) for the first time-Was that a mistake?It looked like they needed nutrients. I do not have a ph meter,and use bottled water. What can I do or buy that would help these AK47's stay alive?